# Example of nonlinear time-transient electromagnetic simulation using EMS for SOLIDWORKS

Article by Arvind Krishnan updated June 2, 2016

###### Article

This is a test rig presented by N. Allen and D.Rodger from the School of Engineering, University of Bath to validate a nonlinear time-transient electromagnetic simulation. The 3D representation of the rig is shown below in figure 1 along with the dimensions. A link to the paper can be found here.

Figure 1 – Problem setup

This problem is a part of the TEAM series and is called TEAM Workshop Problem 24. Most real life problems in Electromagnetics are time-transient in nature. So it is extremely important to choose a Simulation package that can handle time transient simulation well. This is also essential for problems involving coupled transient magnetic and motion multi-physics simulation. In this short article we will examine how EMS for SOLIDWORKS compares with the experimental measurements documented by the authors.

## Problem setup

The problem setup consists of a rotor mounted on a nonmagnetic stainless steel shaft and a stator fixed inside a swinging nonmagnetic cage which can move relative to the shaft. The dimensions of the solid steel rotor and stator are shown as per figure 1 and the solid 3D model created using SolidWorks is represented in figure 2.

Figure 2 – 3D model created using SOLIDWORKS

The material properties are all specified inside EMS as per the paper. EMS has its own fully customizable material library where users can use existing materials or create new materials for simulation. A step voltage of 23.1V is applied to the coils which are connected in series and have a combined resistance of 3.09 Ohms. The objectives of the simulation are as follows –

1. Compute the resulting coil current as a function of time and compare it with measurement.
2. Compute the torque acting on the rotor and compare it with measurement.
H (A/m)B (Tesla)
0.000e+000  0.000
1.000e+003  1.000
4.000e+003  1.413
8.010e+003  1.594
1.601e+004  1.751
2.402e+004  1.839
3.203e+004  1.896
4.003e+004  1.936
4.804e+004  1.967
6.405e+004  2.008
8.007e+004  2.042
9.608e+004  2.073
1.121e+005  2.101
1.281e+005  2.127
1.441e+005  2.151
1.761e+005  2.197
2.081e+005  2.240
2.722e+005  2.325
3.042e+005  2.370
3.362e+005  2.420
3.960e+005  2.500

## Materials

The coils are made of Copper (a good conductor) and the stator and rotor are made from ferro-magnetic material whose B-H curve is given in the table below. Note that EMS can support any user defined materials with its own B-H curve for simulation. The program also comes with its own library of materials. The library contains over 200 commonly used materials under the category of steels, conductors, insulators, cables, ceramics, substrates, semiconductors, biological materials etc.

B-H curve

### EMS Results

The results obtained from EMS is plotted and compared against experimental values. It is observed that EMS results closely match the expected results. Also some key plots like Magnetic flux density, Current density etc are also shown at a particular time step.

## EMS Result plots

The magnetic flux density (B) and the current density (I) at time = 0.02 sec is shown below.

## EMS for SOLIDWORKS

EMS for SOLIDWORKS is the first and only completely embedded Gold Certified software for SOLIDWORKS which helps SOLIDWORKS users study their magnetic, electric and electromagnetic designs seamlessly. It can utilize the geometry created using SOLIDWORKS directly for simulation. Its user interface emulates SOLIDWORKS and hence there is no learning curve associated with the EMS software for SOLIDWORKS users.